/** cp1.c
 * version 1 of cp - uses read and write with tunable buffer size
 *
 * usage: cp1 src dest
 */
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>

#define	BUFFERSIZE	4096
#define	COPYMODE	0644

void oops(char *, char *);

main(int ac, char * av[])
{
	int	in_fd, out_fd, n_chars;
	char	buf[BUFFERSIZE];
					/* check args */
	if (ac != 3)
	{
		fprintf(stderr, "usage: %s source destination\n", * av);
		exit(1);
	}
					/* open files */
	if ((in_fd=open(av[1], O_RDONLY)) == -1)
		oops("Cannot open", av[1]);

	if ((out_fd=creat(av[2], COPYMODE)) == -1)
		oops("Cannot creat", av[2]);
					/* copy files */
	while ((n_chars = read(in_fd, buf, BUFFERSIZE)) > 0)
		if (write(out_fd, buf, n_chars) != n_chars)
			oops("Write error to ", av[2]);
	if (n_chars == -1)
		oops("Read error from ", av[1]);
					/* close files */
	if (close(in_fd) == -1 || close(out_fd) == -1)
		oops("Error closing files", "");
}

void oops(char * s1, char * s2)
{
	fprintf(stderr, "Error: %s", s1);
	perror(s2);
	exit(1);
}
